PDM software or PLM software: what's the difference?

Product lifecycle management (PLM) is often
defined as an evolutionary improvement of
product data management (PDM).
However, it's much easier to decide what you need by focusing on the
technical differences between PDM and PLM.

Product lifecycle management is a cross-organizational tool
for collecting, controlling and publishing approved product
configurations. In PLM, part and document objects are represented in a
database, and managed by change forms. Unlike PDM, part and document
records exist independently of files.

There are good reasons — technical and operational — why these solutions
have become distinct.

Technical differences between PDM & PLM

PDM: A file-based system for managing 3D models of physical objects

Computer files are the building blocks of a 3D CAD model. Multiple files
may be combined to model an assembly of parts or, sometimes, a single part. A single
parameter-driven file can also represent several parts with distinct part
numbers.

CAD software usually requires a proprietary file format that often
contains links between related CAD files. Part information can be attached
to file records ("model annotations"). Supporting documentation that's not
contained in the model (requirements, procedures, qualified sources, etc.) may need to be managed elsewhere. Change workflows operate on
individual files, not necessarily complete part objects.

There may not be a one-to-one relationship between a CAD file
and a part, and a CAD file generally can't represent non-mechanical
information required for production.

In short, the computer folder/file system is the natural data environment
for working with CAD files. Mechanical 3D CAD models require specialized file managers —
a product data management (PDM) tool — to create, edit and move file
relationships. Item re-use often requires copying the physical file from one
model to another, or coordinating several models. Most CAD vendors provide
their own PDM tool for these purposes.

PLM: A database system for managing products & processes

A relational database is the natural data environment for PLM objects.
These objects can represent a physical part, assembly or document; a
customer requirement or supplier part; a change process; and many other data
types. These records contain useful properties over the object's
design lifecycle: part/document number, item category, revision, title, unit of measure,
bill of
materials, cost, mass, regulatory compliance details, file attachments, etc. These objects are easily linked to
other objects to build a product structure. Objects and their relationships
are quite flexible: they're simple to create, customize, revise, re-use and remove.

PLM systems have different classes of objects (primarily parts, documents and
change forms) with distinct properties and behaviors. A
bill of
materials is a collection of database objects;
document references and
approved vendor sources are object lists.
Change forms can directly act on
objects by, for instance,
releasing a revised part and automatically ensuring all BOM components and
supporting documents are released simultaneously. An
object's Appears On (or "where used") displays its parent
assemblies, referencing items and releasing/canceling
change forms. Advanced configuration management concepts, such as
revision-interchangeability on BOMs, can be handled automatically.

Since a PLM system is a database, it easily
supports part-driven CAD (like
Altium Designer and
OrCAD CIS)
and data transfers to ERP/MRP.

In a PLM system, a CAD file (or set of files) is simply one of many
attributes that describe the part. Non-CAD files can also be attached,
such as a Microsoft Word specification, vendor datasheet PDF, or even
a customer email. Files can be attached to change forms and organization
records. A PLM system can index the text contents of a file, and
open a file with whatever Windows application recognizes its file type.

File attachments can have different contexts. Revision files directly
define how to fabricate, purchase or assemble the item. Item files provide
background or history. External links point to useful resources outside of
the PLM system, such as vendor web pages.

The PLM many-to-many product structure simplifies object re-use by
adding links between objects, rather than by physically copying them.

Operational differences between PDM & PLM

There is no known way to handle the complex interrelationship between parts
without access to a well designed Product Data Management system. A PLM system is even more useful!

There can be overlap between PDM and PLM roles. In many companies, PLM
and PDM tools are used side-by-side.

A PDM system has deep knowledge about the CAD file model; a PLM system has
broad knowledge about the product definition and relationships.

Specialized design environments (like CAD+PDM) feed the PLM system

CAD models exist within the computer file system as folder/file
hierarchical trees. A file is
usually re-used by copying it into a new model, and a design change may need
to update many interrelated files.

Consider the various design disciplines that go into a new product:

industrial, mechanical, electronic and software design

documentation and graphics for installation and use

requirements, specifications and procedures

All of these require some type of "design environment": mechanical CAD
with model management; electronic circuit design and simulation; software development
with source control;
graphics tool; or simply a word processor. Each of these design environments produce design
files that are
coordinated with the other disciplines to ensure a coherent product.

The CAD model won't include non-mechanical documents such as schematics
and procedures, or essential physical item records such as user manuals. PDM
tools often ignore documentation affecting marketing, quality, product
support, service, and disposal. PDM attributes may be locked within
proprietary file formats, and can't easily be shared with other
applications.

A PDM tool is most useful for managing interrelated file-based models within a
specific discipline, such as mechanical design.

The PLM system feeds design, test, procurement, production and service

Product information is divided between what's required specifically for
engineering development, and what's needed to manage, purchase, manufacture and
service the product.

The PLM system contains — and closely controls — the product
data that users need from the development process. It ensures that

Previously-developed data is quickly found and may be easily
evaluated for re-use

Product data useful to the company is shared, rather than embedded in
proprietary file formats for a specific design discipline

Pre- and post-production design data is clearly segregated from
production data using lifecycle tags

Rules for part and document numbering are followed, and workflow for
changes is enforced

Parts are categorized to ensure all required data is easily
identified

Procedures for assembly, test, inspection, sales, installation and
use are coordinated between affected departments

Approved vendor sources are documented and shared with procurement, and
AVL changes are controlled

Information approved for production is protected from uncontrolled
changes

Changes to any previously-approved data is reviewed by the
affected groups, including those outside engineering

Approved product configurations can be exported accurately
and consistently to downstream computer systems and contract
manufacturers

Historical information — changes approved, items
affected, why the change occurred, and who approved it — is always
available

Data is easily shared with other "database aware" software (such as
electronics CAD and ERP/MRP), and exported in flexible text-based file
formats

PLM software manages an approved configuration of your complete product over the entire product
life cycle.

A PLM solution is most useful for defining, controlling and sharing complex,
multi-discipline, or fast-changing products.

PLM software for communication & control

The normal mechanical CAD/PDM/PLM interaction consists of: creating part numbers within
the PLM system; using those part numbers during your CAD/PDM model
development; exporting the bill of materials from CAD for import into PLM; and
attaching models (file sets) as approved, controlled snapshots of the 3D
model. The file set (and related specifications and procedures) is approved within the PLM system and released to your production and
supply chain.

PLM coordinates design intent and provides an orderly
flow of approved data. PLM ensures that only the correct parts are
ordered, produced and assembled according to valid & approved documentation.
PLM is the central repository of the product definition: requirements;
drawings; supplier datasheets; test results; assembly, test and inspection
procedures; user documentation; and technical field support materials.

PLM systems prevent costly errors related to unapproved part
substitutions, out-of-date documentation, incorrect part numbers, and even
many clerical errors in transferring final designs into production. They can
also answer questions about what had previously been used, who made changes
and why, and what alternatives were considered and rejected.

Virtually unlimited change forms and change workflows
that can be uniquely tailored to a specific department's
needs, so that upstream (marketing) and downstream (customer
support, field service) organizations can manage their part
of the product life cycle using their own change processes.